1. Field of the Invention
The invention relates to a driving system of a self-driving cable cableway car which system comprises on both sides of a vertical plane, in which the bearing cable is disposed, driving chains revolving about chain sprocket wheels with horizontal rotational axes. The driving chains bear clamping units with friction linings for contact on the bearing cable, and lead rails disposed on opposite sides of the bearing cable. The clamping units, during the revolution of the driving chains, are guided through a particular interspace between the bearing cable and one of the lead rails and herein the friction linings of the clamping units are pressed onto the bearing cable by the rollers rolling out on running faces. Also, a particular lead rail is preloaded by a spring device against the particular clamping unit located in the interspace between the lead rail and the bearing cable.
2. Description of the Related Art
Although there is a multiplicity of proposals for implementing self-driving cableways, they have so far under conditions of practical requirements only been applicable to special applications, for example rescue cars. The economic application for cableway cars under continuous operation has so far not been possible. For such it must not only have high climbing ability and driving speed, it must have sufficient wear resistance. In addition, it is essential that the ratio of unladen weight to payload is not too high. For the climbing ability a value of at least 100% is conventionally required. For driving speed a value of at least 2 to 5 m/s is desired. Under utilization intensities customary for cableways, hundreds of operating hours and more are reached annually and appropriate wear resistance must be given. Acceptable weight ratios between tare and net weight should be better than three, and preferably better than two.
To attain sufficiently large friction faces between friction elements and bearing cable, crawler chain-like structures are conventionally utilized for self-driving cableways. Elastically lined friction elements are prescribed herein. To be able to generate sufficiently high forces for pressing the friction elements onto the bearing cable, the rollers, which roll out on corresponding running faces and press the friction elements onto the bearing cable, are implemented such that they are hardened, as are the running faces for the rollers.
Apart from an embodiment in which a single driving chain revolving in a vertical plane is provided, AT 263 851 also discloses an embodiment of a driving system of a self-driving cableway car, in which on both sides of the vertical plane in which the bearing cable is disposed, one driving chain revolves around chain sprocket wheels with horizontal axes. On the chain links are disposed clamping plates which are guided in the particular section of the driving chains adjacent to the bearing cable through a particular interspace between a driving rail and the bearing cable. On the clamping plates, with the interspacing of springs, rollers are pivoted which roll out on running faces of the lead rails, wherein the springs are compressed and the clamping plates are pressed onto the bearing cable. This system has the disadvantage of complicated implementations of the clamping units disposed on the driving chains. Each clamping unit requires a spring device which must exert sufficient compression force on the bearing cable and which, due to the continuous working movements, with each revolution of the chain is exposed to very high wear and therefore must be implemented with corresponding expenditures and complexities. Apart from the increased constructional expenditure, this leads in particular to relatively high unladen weight of the driving system and, consequently, of the entire cableway car which critically impairs the economy of the system.
In the driving system disclosed in CH 462 225 the clamping plates disposed on the chain links are loaded by stationary rollers under the action of springs, as is customary in tracklaying trucks. The spring-loaded rollers press the clamping plates onto the bearing cable in the particular section of the chain located in the proximity of the rollers. The spring-loaded rollers must drive over the gap between the individual clamping plates. Due to this continuous driving over rail joints not only rough running results, but also high wear. Thereby only a relatively short service life is attained, in particular if the constructional expenditure and the weight are not supposed to be too high.
In the system of CA 1096368 A on the opposing sides of the bearing cable are provided driving chains disposed in a common plane. On the chain links are supported clamping plates which are pressed from above and below against the bearing cable. To exert pressure onto the clamping plates, again, as is known from crawler vehicles, a roller unit is provided. The rollers in this case are pivoted on separate chains which revolve about a carrier within the region encompassed by the driving chains. To clamp in the bearing cable between the opposing clamping plates, the carriers are pulled together by means of piston-cylinder units. In addition, a spring device is furthermore provided for exerting a prestress of the two carriers directed against one another. The apparatus expenditure of this device is substantially higher than in the cited constructions of AT 263 851 and CH 462 225 and the weight requirements for economic operation of a self-driving cableway car, in particular if such is to be employed as a means of transportation for persons, cannot even be approximately maintained. The rollers acted upon by the clamping plates, again, also drive over the joints between the clamping plates, which results in problems involving wear. Furthermore, in the region in which the clamping plates are pressed from above and from below onto the bearing cable, no bearing rollers of the cableway car roll out on the bearing cable such that a cableway car would only be realizable with a large overhanging construction.
A system of the type described in the introduction is disclosed in DE 202 13 353 U1. In the driving system disclosed in this document, the rollers, by means of which the friction linings of clamping units are pressed onto the bearing cable, are rotatably supported on U-profiles. The running faces, on which these rollers roll out, are disposed on the clamping units, which are carried by the chain links of the driving chains. During the revolution of the driving chains, the rollers drive over the joints between the individual clamping units, which results in rough running and high wear.